Loop coilantenna

• US 20050092836A1
• Filed: 10/29/2004
• Published: 05/05/2005
• Est. Priority Date: 10/29/2003
• Status: Abandoned Application

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Kudo, Kazuhiro
• Application Number:
  US10/975,395
• Publication Number:
  US 20050092836A1
• Time in Patent Office: Days
• US Class Current: 235/436
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

This invention constructs an antenna matching circuit able to avoid a bad influence when a conductor, such as a metal, or tag, approaches a reader/writer, and dissolves a communication defect area on the reader/writer and stably maintains a communication distance. In this invention, in a RFID system, when the tag corresponds to the generating area of a magnetic field of the reader/writer, a radio wave for sending information to the reader/writer is outputted by operating a control circuit of the tag by electric power generated in an antenna coil of this corresponding tag. A conductor is arranged near the antenna coil of the reader/writer and an eddy current is intentionally flowed. Thus, the communication defect between the reader/writer and the tag approaching this reader/writer is reduced.

Claims

1. A loop coil antenna used in a RFID reader/writer circuit, said antenna comprising:

an antenna coil, of a reader/writer circuit, arranged in a loop for receiving electrical signals from a driving circuit and for generating an electromagnetic field for communicating with an RFID tag; and

a conductor insulated from said antenna coil arranged within an interior of said loop.

2. The loop coil antenna according to claim 1, wherein said driving circuit is integrally related to said reader/writer circuit.

3. The loop coil antenna according to claim 1, wherein said driving circuit is separated from said reader/writer circuit.

4. The loop coil antenna according to claim 1, wherein said conductor is constructed by a metallic plate buried in the interior surrounded by the antenna coil of the reader/writer.

5. A method of operating an RFID tag system, the system comprising

a reader/writer circuit and an associated tag, the method comprising the acts of:

generating an electromagnetic field by the reader/writer circuit, wherein the reader/writer comprises a conductor insulated from and surrounded by an antenna coil, provided in a substrate; and

operating a circuit of an RFID tag to output a radio wave from the tag when it recieves said electromagnetic field.

6. The method according to claim 6, further comprising the act of communication information between the tag and the reader/writer.

7. A method of making an RFID system with reduced interference comprising:

forming a reader/writer loop coil antenna in a substrate for generating an electromagnetic field, wherein the reader/writer comprises a conductor insulated from and surround by said substrate; and

providing an associated tag for producing a radio wave when introduced to said electromagnetic field.

8. The method according to claim 7, further comprising providing a driving circuit for said reader/writer.

9. The method according to claim 8, further comprising connecting said driving circuit to said reader/writer by wires.

10. The method according to claim 8, further comprising integrating said driving circuit with said reader/writer circuit.

11. A loop control antenna comprising:

a reader/writer substrate separated from an antenna substrate, wherein both of said substrates are made of a non-electrically conductive resin material;

a driving circuit, mounted on said substrate, for reading and writing information;

an antenna coil constructed as a loop antenna mounted on said antenna substrate;

an antenna matching circuit mounted on said antenna substrate;

an electrically conductive metallic plate mounted on said antenna substrate for acting as a conductor; and

wiring connecting said reader/writer circuit and said driving circuit.

12. The loop antenna according to claim 11, wherein said conductive plate is insulated and surrounded by the antenna coil.

13. A reader/writer of a loop control antenna including:

a reader/writer substrate;

a metallic plate conductor, mounted in the interior of said substrate, for generating an eddy current;

a antenna coil surrounding and insulated from said metallic plate; and

an antenna matching circuit connected to said antenna coil.

14. A reader/writing of a loop control antenna including:

a reader/writer substrate;

a driving circuit, mounted on said substrate, for reading and writing information;

an antenna substrate;

an antenna coil constructed as a loop antenna mounted on said antenna substrate;

an antenna matching circuit mounted on said antenna substrate; and

an electrically conductive metallic plate mounted on said antenna substrate, wherein said antenna substrate and said coil and matching circuit mounted thereon are integrally connected with said reader/writer substrate and said driving circuit mounted thereon.